This invention relates to a thrombectomy device. This invention also relates to an associated method for performing a thrombectomy.
The presence of clot within the human vascular system is always abnormal. It is the cause of significant medical disease. In the arterial system, it can lead to an inability for blood to perfuse and nourish the target tissues with oxygen, a condition known as ischemia. In the venous system, clot can obstruct the drainage pathways, leading to poor blood drainage back to the heart and a buildup in back pressure. This condition is known as venous stasis and venous hypertension, respectively and may cause significant damage to the affected tissues. In some cases, venous clot may also break off and travel to the heart and lungs. This condition is known as pulmonary embolism and is often fatal.
Because of the above-discussed deleterious effects of vascular clot, when such clot is discovered, a treatment modality is almost always undertaken. Several options are available: 1) the patient may be placed on blood-thinning medications (heparin or coumadin) to help dissolve the clot, 2) surgical intervention may be used to remove the clot, or 3) catheters may be inserted through the skin and directed into the affected vessel, with aid of real-time x-ray fluoroscopy. In the last case, several additional options are available. First, clot dissolving enzymes may be infused through the catheter. This technique, however, is time-consuming and the enzymes are expensive. Second, suction may be used to aspirate clot. Lastly, miniaturized blades, rotors, water jets may be used to break up the clot into smaller pieces. This process is beneficial since small fragments are better tolerated by the body and/or they are easier to aspirate via suction without frequent catheter clogging.
Any time suction is used as a primary of secondary method to remove clot, however, blood loss is a real concern. Clot is frequently surrounded by flowing unclotted blood. There is no known way to selectively aspirate only clot and exclude the unwanted blood. To the contrary, suction will preferentially aspirate blood since it is liquid and flowing. Attempts to "latch on" to clot fragments via sudden suction are usually only partly successful and even so, large amounts of blood may be lost in the process.
Depending on multiple factors, including the vascular pressure, flow rates, the configuration of the native vessel and the clot, etc., it may be necessary to aspirate blood volumes that are several orders of magnitude greater than the clot volumes removed. Since any blood loss is undesirable and only several hundred cc's of blood may be aspirated from an adult at a given time without causing death, inadvertent yet obligatory blood loss is often the limiting factor in the ability to continue and complete the aspiration of visualized clot.